A predicable amount of “white noise” (also known as “random noise”) inherently exists in all electronic equipment. In an audio system this noise sounds like a waterfall or the hiss of an FM (frequency modulation) radio tuned between stations. In a video system this noise appears as grainy movement or “snow” in the image. White noise cannot be prevented or removed without altering the original signal. “Interference” is another type of electrical signal contamination which arises from extraneous sources such as AC (alternating current) power lines and ambient electromagnetic fields such as radio and television signals. Interference typically contaminates an electrical signal by coupling with the signal at the interface between separate pieces of electronic equipment. In audio systems interference can cause audible hum, buzz, clicks, pops and other degradations of the audio. In video systems interference can cause hum bars, specks and other degradations of the image.
An interface between two pieces of electronic equipment generally includes both physical and electrical characteristics. More particularly, such an interface includes line driver circuitry and an output connector at the source electronic equipment, an input connector and line receiver circuitry at the destination electronic equipment, and a cable which runs between the output connector and the input connector. One end of the cable includes a first cable connector which mates with the output connector, and the other end of the cable includes a second cable connector which mates with the input connector. To a large extent, the immunity of an interface to interference is determined by the interface type. Two types of interfaces that are used in consumer electronic equipment today are balanced interfaces and unbalanced interfaces. Coaxial connectors, commonly known as “RCA” connectors and sometimes also referred to as Institute of High Fidelity (IHF) connectors, are the de facto standard type of connectors employed today to carry audio and video electrical signals between consumer electronic equipment. The name “RCA” derives from the Radio Corporation of America, which introduced the original RCA connector design in the early 1940s.